In order to increase the travel stability of automobiles when they turn or travel in a straight line, the following automobiles are starting to be practically used: automobiles each including a mechanism configured to steer the rear wheels in accordance with the travel speed of the vehicle, and the movements of the steering angles of the front wheels, when the front wheels are steered by operating the steering wheel, or a mechanism configured to adjust the toe angles of the rear wheels.
For example, Japanese Unexamined Patent Application Publication No. 2009-173192 (hereinafter JP '192) discloses rear wheel steering devices configured to steer respective rear wheels in accordance with the steering angle of a steering wheel (steering angles of front wheels). The rear wheel steering devices of JP '192 each includes a toe control actuator connected to a knuckle supporting the corresponding one of the right and left rear wheels. The rear wheel steering devices control the respective knuckles independently of each other by the toe control actuators so as to steer the rear wheels in the same direction as or in the direction opposite to the steering angles of the front wheels, or control the toe angles of the rear wheels by shifting the steering angles of the rear wheels, so that the vehicle can stably turn or travel in a straight line.
The Japanese Unexamined Patent Application Publication No. 2013-159131 (hereinafter JP '131) discloses a rear wheel steering device configured to steer right and left rear wheels together. This rear wheel steering device includes a steering housing fixed to the vehicle body; a rear wheel steering shaft axially movably supported by the steering housing; a pair of tie rods coupled to the respective ends of the rear wheel steering shaft; and knuckle arms corresponding/coupled to the respective tie rods. By axially moving the rear wheel steering shaft, this rear wheel steering device can change the respective steering angles of the right and left rear wheels.